This proposal examines the neurocognitive factors that contribute to risky decision making in HIV + and drug dependent individuals. Because risky behaviors that lead to HIV transmission are often associated with immediate reward, understanding how individuals process reward, in terms of their HIV and drug use status, would shed light on mechanisms involved in risky decision making and inform treatment strategies. Our prior research in HIV+ and drug dependent individuals has indicated that these two populations have a heightened sensitivity to learning a stimulus-reward association. Their ability to subsequently ignore a learned reward when it is presented in a novel, irrelevant context is impaired. This characteristic simulates a real-world situation in which a previously learned reward (e.g., heroin syringe) is viewed out of context (e.g., insulin needle) but cannot be ignored and prompts drug craving. We have found that factors contributing to one's ability to ignore context-irrelevant reward include working memory capacity, drug use history, impulsivity traits, and motor function. Moreover, these factors can predict attention-to-reward behaviors six months beforehand. In order to better understand the mechanisms underlying this relationship, the proposed project will examine the neurocognitive processes that direct one's attention to reward. Methods will combine a cognitive task that measures attentional bias for reward with functional magnetic resonance imaging (fMRI). Data will be obtained from populations that include HIV+ individuals with and without a history of drug dependence, HIV - individuals with a history of drug dependence, and healthy controls. In order to measure how the value of reward changes over time (and becomes more difficult to ignore), volunteers will be assessed at two time points six months apart. The overarching hypothesis is that HIV-related brain changes interfere with reward processing, which is further compounded by drug abuse. This leads to heightened, sustained reward salience and increases a person's vulnerability to risky behaviors. Neuroimaging results will reveal whether strategies for ignoring reward are bottom-up (attached to basic reward salience) or top-down (relying on cognitive control). This information will highlight differences between individuals who can successfully ignore reward when necessary vs. those who cannot, and the factors that contribute to both types of behaviors. Knowing how reward is processed in the brain to influence cognition and behavior (e.g., top-down vs. bottom-up mechanisms) could alter clinical practice in terms of developing harm reduction strategies and teaching self-control techniques to high-risk populations before they acquire HIV.